The present invention relates to a display device, and, more particularly, to an active-matrix type liquid crystal display device when exhibits an enhanced response speed.
In an active-matrix type liquid crystal display device, on a liquid-crystal-side surface of one of a pair of substrates which face each other in an opposed manner with liquid crystal material disposed therebetween, for example, there are gate signal lines which extend in the x direction and are arranged in parallel in the y direction, and drain signal lines which extend in the y direction and are arranged in parallel in the x direction. Regions which are defined by these respective signal lines constitute pixel regions, and a plurality of these respective pixel regions are arranged in a matrix array to form a liquid crystal display part.
Here, each pixel region includes a switching element which is driven in response to a scanning signal received from one gate signal line and a pixel electrode to which a video signal is supplied from one drain signal line through the switching element. An electric field is generated between the pixel electrode and a counter electrode, which is formed on the above-mentioned one substrate or the other substrate, and the optical transmissivity of the liquid crystal is controlled based on the electric field.
The optical transmissivity of the liquid crystal is determined based on the amount of potential difference (gray scale) of the video signal (voltage) applied to the pixel electrode with respect to the reference signal (voltage) applied to a counter electrode. Here, for example, for preventing a polarization of the liquid crystal, there is a known method in which a positive-side gray scale voltage are generated and a negative-side gray scale voltage with respect to the above-mentioned video signal, and these gray scale voltages are applied alternately, for example.
In such pixel driving, while there is a known method in which the center voltage of the video signal is always fixed irrespective of the amplitude of the signal, as shown in FIG. 12A, there is also a known method in which the center voltage of the video signal is decreased corresponding to an increase in the amplitude of the signal, as shown in FIG. 12B. That is, the pixel is configured to be driven by forming the respective gray scale voltages such that an average value of the positive-side gray scale voltage and the negative-side gray scale voltage is increased with respect to the reference signal supplied to the counter electrode along with a decrease in the signal amplitude of the video signal (see Japanese Unexamined Patent Publication Hei 7(1995)-92937 (patent literature 1)).